.app-header {
  display: flex;
  align-items: center;
  padding: 0 24px;
  background: #FFFFFF;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  position: fixed;
  width: 100%;
  z-index: 1000;
  top: 0;
  left: 0;
}

.header-left {
  display: flex;
  align-items: center;
  margin-right: 24px;
}

.sidebar-toggle-btn {
  color: #001529;
  margin-right: 16px;
  transition: color 0.3s;
}

.sidebar-toggle-btn:hover {
  color: #1890ff;
}

.app-title {
  margin: 0;
  color: #001529;
}

.header-right {
  display: flex;
  align-items: center;
  margin-left: auto;
}

.header-notification {
  cursor: pointer;
  transition: color 0.3s;
}

.header-notification:hover {
  color: #1890ff;
}

.notification-icon {
  font-size: 18px;
  color: #001529;
}

.user-info {
  display: flex;
  align-items: center;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 4px;
  transition: background-color 0.3s;
}

.user-info:hover {
  background-color: rgba(0, 0, 0, 0.02);
}

.user-avatar {
  background-color: #1890ff;
}

.username {
  color: #001529;
  margin-left: 8px;
  font-size: 14px;
}

@media (max-width: 768px) {
  .username {
    display: none;
  }
}